Grease a small baking dish, or small vessel with side walls, with non-stick spray. Line with parchment paper and spray the parchment also, set aside.
For the first layer: Bring a saucepan of water over medium heat to a simmer. Melt the butter in a heat safe bowl over the top of the saucepan.
Remove from heat, add in sugar, cocoa powder and whisk until well combined. While whisking vigorously, very slowly pour in beaten egg in a thin stream.
Return the bowl over the simmering water and stir until the mixture starts to thicken.
Remove from heat and fold in graham cracker crumbs, coconut, and almonds, then toss until evenly combined.
Press the mixture into the prepared baking dish. Chill in the freezer while preparing the filling. (The bottom layer shouldn't be warm when adding the middle layer.)
For the second layer: add powdered milk and heavy cream to the bowl of an electric mixer (can also whisk by hand). Whisk vigorously to dissolve powdered milk. Add in butter, powdered sugar, and vanilla; beat mixture until very light and fluffy (icing consistency).
Spread mixture into an even layer over first layer. Chill in the freezer while melting chocolate (otherwise the warm chocolate can melt this layer).
For the third layer: Melt dark chocolate along with butter in a heat proof bowl. Set over the saucepan of simmering water until smooth (or in the microwave in a microwave safe bowl in 20 second intervals, stirring between each, until melted and smooth).
Spread mixture into an even layer over top of the filling layer (spread quickly before chocolate begins to set). Chill in the freezer until chocolate has set.
Cut into squares and serve.